I am finding it difficult to select a HUB router for DMVPN (Hub-Spoke topology) where there are 42 spokes with ADSL2+ connections and a 100Mb Ethernet at the HUB site. Will a Cisco 2821 router be enough to handle that amount of VPN traffic or will an upgrade be required?
thanks is advance.
200 Mbps (100 Mbps duplex) is likely too much for a 2821. However, if the 42 ADSL2+ connections sum less or you expect links not hit max, you can size for expected load.
Attached is a reference sheets for VPN performance. Take note of Table 5 (don't forget to allow for duplex bandwidth).